Copper alloy and process for producing the same

ABSTRACT

A copper alloy that has a specific chemical composition, the balance being Cu and impurities, in which the relationship between the total number N and the diameter X satisfies the following formula (1). This copper alloy is obtained by cooling a bloom, a slab, a billet or an ingot in at least a temperature range from the temperature of the bloom, the slab, the billet or the ingot just after casting to 450° C., at a cooling rate of 0.5° C./s or more. After the cooling, working in a temperature range of 600° C. or lower and further heat treatment of holding for 30 seconds or more in a temperature range of 150 to 750° C. are desirably performed. The working and the heat treatment are most desirably performed for a plurality of times.
 
log  N &lt;0.4742+17.629×exp(−0.1133× X )  (1)
 
     wherein N means the total number of precipitates and inclusions, having a diameter of not smaller than 1 μm which are found in 1 mm 2  of the alloy; and X means the diameter in μm of the precipitates and the inclusions having a diameter of not smaller than 1 μm.

TECHNICAL FIELD

The present invention relates to a copper alloy, which can be producedat low cost and has excellent mechanical and electrical properties. Thisinvention also relates to a process for producing the said copper alloy.This copper alloy is suitable for electrical and electronic parts,safety tools, and the like.

Examples of the electric and electronic parts include connectors forpersonal computers, semiconductor plugs, optical pickups, coaxialconnectors, IC checker pins and the like in the electronics field;cellular phone parts (connector, battery terminal, antenna part),submarine relay casings, exchanger connectors and the like in thecommunication field; and various electric parts such as relays, variousswitches, micromotors, diaphragms, and various terminals in theautomotive field; medical connectors, industrial connectors and the likein the medical and analytical instrument field; and air conditioners,home appliance relays, game machine optical pickups, card mediaconnectors and the like in the electric home appliance field.

Examples of the safety tools include excavating rods and tools such asspanner, chain block, hammer, driver, cutting pliers, and nippers, whichare used where a possible spark explosion hazard may take place, forexample, in an ammunition chamber, a coal mine, or the like.

BACKGROUND ART

A Cu—Be alloy has been known as a copper alloy that is used for theabove mentioned electric and electronic parts. This alloy isstrengthened by age precipitation of the Be, and contains a substantialamount of Be. This alloy has been extensively used as a spring materialor the like because it is excellent in both tensile strength andelectric conductivity. However, Be oxide is generated in the productionprocess of Cu—Be alloy and also in the process of forming to variousparts.

Be is an environmentally harmful material as is Pb and Cd. Particularly,the substantial amount of Be in the conventional Cu—Be alloynecessitates a treatment process for the Be oxide in the production andworking of the copper alloy. The treatment process leads to an increasein the production cost. It also causes a problem in the recyclingprocess of the electric and electronic parts. Thus the Cu—Be alloy is aproblematic material from the environmental point of view. Therefore, amaterial, which is excellent in both tensile strength and electricconductivity and in which the content of environmentally harmfulelements such as Be is as low as possible, is desired.

A copper alloy called Corson alloy, in which Ni₂Si is precipitated, isproposed in Patent Document 1. This alloy has a relatively good balanceof tensile strength and electric conductivity among alloys free fromenvironmentally harmful elements such as Be, and has a electricconductivity of about 40% at a tensile strength of 750 to 820 MPa.

However, this alloy has limitations in enhancing strength and electricconductivity, and this still leaves a problem from the point of productvariations as described below. This alloy has age hardenability due tothe precipitation of Ni₂Si. If the electric conductivity is enhanced byreducing the contents of Ni and Si, the tensile strength issignificantly reduced. On the other hand, even if the contents of Ni andSi are increased in order to raise the precipitation quantity of Ni₂Si,the electric conductivity is seriously reduced, although the rise oftensile strength is limited. Therefore, the balance between tensilestrength and electric conductivity of the Corson alloys is disrupted inan area with high tensile strength and in an area with high electricconductivity, consequently narrowing the product variations. This isexplained as follows.

The electric resistance (or electric conductivity that is the inversethereof of an alloy is determined by electron scattering, and fluctuatesdepending on the kinds of elements dissolved in the alloy. Since the Nidissolved in the alloy noticeably raises the electric resistance(noticeably reduces the electric conductivity), the electricconductivity reduces in the above-mentioned Corson alloy if Ni isincreased. On the other hand, the tensile strength of the copper alloyis obtained due to an age hardening effect. The tensile strength isimproved more as the quantity of precipitates grows larger, or as theprecipitates are dispersed more finely. The Corson alloy has limitationsin enhancing the strength from the point of the precipitation quantityand from the point of the dispersing state, since the precipitatedparticle is made up of Ni₂Si only.

Patent Document 2 discloses a copper alloy with a satisfactory wirebonding property, which contains elements such as Cr and Zr and has aregulated surface hardness and surface roughness. As described in anembodiment thereof, this alloy is produced based on hot rolling andsolution treatment.

However, the hot rolling needs a surface treatment for preventing hotcracking or removing scales, which result in a reduction in yield.Further, frequent heating in the atmosphere facilitates oxidation ofactive additive elements such as Si, Mg and Al. Therefore, the generatedcoarse internal oxides problematically s cause deterioration ofcharacteristics of the final product. Further, the hot rolling andsolution treatment need an enormous amount of energy. The copper alloydescribed in Patent Document 2 thus has problems in view of an additionin production cost and energy saving because this alloy is based on thehot working and solution treatment, Furthermore, deterioration ofproduct characteristics (bending workability, fatigue characteristic andthe like besides tensile strength and electric conductivity), which isresult of generation of coarse oxides and the like.

On the other hand, the safety tool materials have required mechanicalproperties, for example, strength and wear resistance matching those oftool steel. It is also required to avoid generating sparks which couldcause an explosion. In other words, excellent spark generationresistance is necessary for the safety tool materials. Therefore, acopper alloy with high thermal conductivity, particularly, a Cu—Be alloyaimed at strengthening by age precipitation of Be has been extensivelyused. Although the Cu—Be alloy is an environmentally problematicmaterial, as described above, it has been heavily used as the safetytool material based on the following.

FIG. 1 is a graph showing the relationship between electric conductivity[IACS (%)] and thermal conductivity [TC (W/m.K)] of a copper alloy. Asshown in FIG. 1, both are almost in a 1:1-relation. Enhancing of theelectric conductivity [IACS (%)] means enhancing of the thermalconductivity [TC (W/m.K)], in other words, enhancing of the electricconductivity inproves the spark generation resistance. Sparks aregenerated by the application of a sudden force by an impact blow or thelike during the use of a tool due to a specified component in the alloybeing burnt by the heat generated by an impact or the like. As describedin Non-Patent Document 1, steel tends to cause a local temperature risedue to its thermal conductivity which can be as low as ⅕ or less of thatof Cu. Since the steel contains C, a reaction “C+O₂→CO₂” takes place,generating sparks. In fact, it is known that pure iron containing no Cgenerates no sparks. Other metals which tend to generate sparks are Tiand Ti alloy. The thermal conductivity of Ti is as extremely low, as lowas 1/20 of that of Cu, and therefore the reaction “Ti+O₂→TiO₂” takesplace. Data shown in Non-Patent Document 2 are summarized in FIG. 1.

However, the electric conductivity [IACS (%)] and the tensile strength[TS (MPa)] are in a trade-off relation, and it is extremely difficult toenhance both simultaneously. Therefore, the Cu—Be alloy was the onlycopper alloy that had sufficiently high thermal conductivity TC whileretaining a tool steel-level high tensile strength in the past.

[Patent Document 1]

Japanese Patent No. 2,572,042

[Patent Document 2]

Japanese Patent No. 2,714,561

[Non-Patent Document 1]

Industrial Heating, Vol. 36, No. 3 (1999), Japan Industrial Furnace

Manufacturers Association, p. 59

[Non-Patent Document 2]

Copper and Copper Alloy Product Data Book, Aug. 1, 1997, issued by JapanCopper and Brass Association, pp. 328-355

[Disclosure of the Invention]

[Subject to be Solved by the Invention]

It is the primary objective of the present invention to provide a copperalloy, which is excellent in ductility and workability with a wideproduction variations and, further, excellent in performances requiredfor safety tool materials, such as thermal conductivity, wear resistanceand spark generation resistance. It is the second objective of thepresent invention to provide a method for producing the above-mentionedcopper alloy.

The “wide production variations” mean that the balance between electricconductivity and tensile strength can be adjusted from a high levelequal to or higher than that of the Cu—Be alloy to a low level equal tothat of a conventionally known copper alloy, by minutely adjustingaddition quantities and/or a production condition.

The “balance between electric conductivity and tensile strength can beadjusted from a high level equal to or higher than that of the Cu—Bealloy” specifically means a state satisfying the following formula (a).This state is hereinafter referred to as a “state with an extremelysatisfactory balance of tensile strength and electric conductivity”.TS ≧648.06+985.48×exp(−0.0513×IACS)  (a)wherein TS represents tensile strength (MPa) and IACS representselectric conductivity (%).

For the bending workability, it is also desirable to ensure a levelequal to that of a conventional alloy such as Cu—Be alloy. Specifically,the bending workability can be evaluated by performing a 90° C.-bendingtest to a specimen at various curvature radiuses, measuring a minimumcurvature radius R, never causing cracking, and determining the ratio B(=R/t) of this radius to the plate thickness t. A satisfactory range ofbending workability satisfies B≦2.0 in a plate material with a tensilestrength TS of 800 MPa or less, which satisfies the following formula(b) in a plate material having a tensile strength TS exceeding 800 MPa.B≦41.2686−39.4583×exp [−{(TS−615.675)/2358.08}²]  (b)

For a copper alloy as safety tool, wear resistance is also required inaddition to other characteristics such as tensile strength TS andelectric conductivity IACS as described above. Therefore, it isnecessary to ensure that wear resistance is equal to that of tool steel.Specifically, a hardness at room temperature of 250 or more in theVickers hardness is regarded as excellent wear resistance.

[Means to solve the Problems]

The present invention involves copper alloys shown in the following (A)to (C), and a method for producing a copper alloy shown in the following(D).

(A) A copper alloy characterized in that the alloy consists of, by mass%, one or more elements selected from Zn, Sn, Ag, Mn, Fe, Co, Al, Ni,Si, Mo, V, Nb, Ta, W, Ge, Te and Se of 0.1 to 20% respectively or intotal, and the balance Cu and impurities; and the alloy satisfies thefollowing formula (1):log N≦0.4742+17.629×exp(−0.1133×X) )  (1)

wherein N means the total number of precipitates and inclusions, havinga diameter of not smaller than 1 μm, which are found in 1 mm² of thealloy; and X means the diameter in μm of the precipitates and theinclusions having diameter of not smaller than 1 μm.

(B) A copper alloy characterized in that the alloy consists of, by mass%, an element selected from Ti of 0.01 to 5%, Zr of 0.01 to 5% and Hf of0.01 to 5%, and one or more elements selected from Zn, Sn, Ag, Mn, Fe,Co, Al, Ni, Si, Mo, V, Nb, Ta, W. Ge, Te and Se of 0.01 to 20%respectively or in total, and the balance Cu and impurities; and thealloy satisfies the following formula (1):log N≦0.4742+17.629×exp(−0.1133×X)  (1)

wherein N means the total number of precipitates and inclusions, havinga diameter of not smaller than 1 μm, which are found in 1 mm² of thealloy; and X means the diameter in μm of the precipitates and theinclusions having diameter of not smaller than 1 μm.

(C) A copper alloy characterized in that the alloy consists of, by mass%, Cr of 0.01 to 5%, and one or more elements selected from Zn, Sn, Ag,Mn, Fe, Co, Al, Ni, Si, Mo, V, Nb, Ta, W. Ge, Te and Se of 0.01 to 20%respectively or in total, and the balance Cu and impurities; and thealloy satisfies the following formula (1):log N≦0.4742+17.629×exp(−0.1133×X)  (1)

wherein N means the total number of precipitates and inclusions, havinga diameter of not smaller than 1 μm, which are found in 1 mm² of thealloy; and X means the diameter in μm of the precipitates and theinclusions having diameter of not smaller than 1 μm.

The copper alloy shown in above (A), (B) or (C) may, instead of a partof Cu, contain one or more elements selected from Mg, Li, Ca and rareearth elements of 0.001 to 2 mass % respectively or in total , and/orone or more elements selected from P, B, Bi, Tl, Rb, Cs, Sr, Ba, Tc, Re,Os, Rh, In, Pd, Po, Sb, Au, Ga, S, Cd, As and Pb of 0.001 to 3 mass %respectively or in total. Further the alloy may contain 0.1 to 5 mass %of Be. In these alloys, it is desirable that the ratio of the “maximumvalue of the average content” and the “minimum value of the averagecontent” of at least one alloy element in a micro area is not less than1.5. The grain size of the alloy is desirably 0.01 to 35 μm.

(D) A method for producing a copper alloy, which satisfies the followingformula (1), comprising cooling a bloom, a slab, a billet or an ingotobtained by melting a copper alloy, having a chemical compositiondescribed in the above (A), (B) or (C) followed by cooling in at least atemperature range from the temperature of the bloom, the slab, thebillet or the ingot just after casting to 450° C., at a cooling rate of0.5° C./s or more,log N≦0.4742+17.629×exp(−0.1133×X)  (1)

wherein N means the total number of precipitates and inclusions, havinga diameter of not smaller than 1 μm which are found in 1 mm² of thealloy; and X means the diameter in μm of the precipitates and theinclusions having a diameter of not smaller than 1 μm.

After the cooling, working in a temperature range of 600° C. or lower,and a further heat treatment holding for 30 seconds or more in atemperature range of 150 to 750° C. are desirably performed. The workingin a temperature range of 600° C. or lower and the heat treatment ofholding in a temperature range of 150 to 750° C. for 30 seconds or moremay be performed for a plurality of times. After the final heattreatment, the working in a temperature range of 600° C. or lower may beperformed.

The precipitates in the present invention mean metals or compounds ofcopper and additive elements and between additive elements, for example,Cu₄Ti in the, alloy containing Ti, Cu₉Zr₂ in the alloy containing Zr,metal Cr in the alloy containing Cr. The inclusions mean, for example,metal oxides, metal carbides, metal nitrides and the like.

[Best Mode for Carrying Out the Invention]

An embodiment of the present invention will be described in detail. Inthe following description, “%” for content of each element represents “%by mass”.

1. Copper Alloy of the Present Invention

(a) Chemical Composition

One of the copper alloy according to the present invention has achemical composition consisting of 0.1 to 20% respectively or in totalof at least one element selected from Zn, Sn, Ag, Mn, Fe, Co, Al, Ni,Si, Mo, V, Nb, Ta, W. Ge, Te and Se (referred to as “the first groupelements” hereinafter) and the balance Cu and impurities.

Each of these elements has an effect of improving corrosion resistanceand heat resistance while keeping a balance between strength andelectric conductivity. This effect is exhibited when 0.1% or morerespectively or in total of these elements is contained. However, whentheir contents are excessive, the electric conductivity is reduced.Accordingly, these elements should be contained at 0.1 to 20%respectively or in total. Particularly, since Ag and Sn contribute tothe increase in strength of the alloy by forming fine precipitates,active use of them is preferred. In the alloy that contains thefollowing second group elements, the lower limit of the first groupelements may be 0.01% because the strength can be maintained the secondgroup elements.

The copper alloy of the present invention may contain an elementselected from 0.01 to 5% of Ti, 0.01 to 5% of Zr and 0.01 to 5% of Hf,and also may contain 0.01 to 5.0% Cr, instead of a part of Cu.Hereinafter, these elements are referred to as the second groupelements. An element selected from Ti: 0.01 to 5%, Zr: 0.01 to 5% and Hf0.01 to 5%

Since Ti, Zr and Hf increase high-temperature strength of the alloy, anelement selected from them can be contained in the alloy of theinvention. The effect appears remarkably when the content of theelements is 0.01% or more respectively. However, if the content exceeds5%, the electric conductivity is deteriorated although the strength isenhanced. Further, segregation of these elements caused in casting makesit difficult to obtain a homogeneous dispersion of the precipitates, andcracking or chipping tends to occur in the subsequent working.Therefore, it is desirable to make the content of these elements 0.01 to5.0% respectively when they are added to the alloy. In order to obtainan extremely satisfactorily balanced state of tensile strength andelectric conductivity, it is desirable to make the alloy contain 0.1% ormore of these elements.

Cr: 0.01 to 5%

Cr is an element that increases strength without making electricconductivity higher. In order to obtain the effect, the Cr content ispreferably 0.01% or more. Particularly, in order to obtain an extremelysatisfactorily balanced state of tensile strength and electricconductivity equal to or more than that of the Cu—Be alloy, a content of0.1% or more is desirable. On the other hand, if the Cr content exceeds5%, coarse metal Cr is formed so as to adversely affect the bendingcharacteristic, fatigue characteristic and the like. Therefore, thepreferable Cr content is 0.01 to 5% when it is added.

For the purpose of increasing high-temperature strength, the copperalloy of the present invention desirably contains, instead of a part ofCu, one or more elements selected from Mg, Li, Ca and rare earthelements of 0.001 to 2% respectively or in total. Hereinafter theseelements are referred to as the third group elements.

Mg, Li, Ca and rare earth elements are easily bonded with an oxygen atomin the Cu matrix, leading to fine dispersion of the oxides, whichenhance the high-temperature strength. This effect is noticeable whenthe total content of these elements is 0.001% or more. However, acontent exceeding 2% could result in saturation, and causes problemssuch as reduction in electric conductivity and deterioration of bendingworkability. Therefore, when one or more element selected from Mg, Li,Ca and rare earth elements are included, the respective or total contentthereof is desirably set to 0.001 to 2%. The rare earth elements meanSc, Y and lanthanide, may be added separately or in a form of mischmetal.

For the purpose of extending the width (ΔT) between liquidus and solidusin the casting, the copper alloy of the present invention desirablyincludes 0.001 to 0.3% respectively or in total of one or more elementsselected from P. B, Bi, Tl, Rb, Cs, Sr, Ba, Tc, Re, Os, Rh, In, Pd, Po,Sb, Au, Ga, S, Cd, As and Pb instead of a part of Cu. However, it isrecommendable not to use As, Pd and Cd because they are detrimentalelements. Hereinafter these elements from P to Pb are referred to as thefourth group elements. Although ΔT is increased by a so-calledsupercooling phenomenon in rapid solidification, ΔT in a thermallyequilibrated state is considered herein as a standard.

The above-mentioned elements are effective for lowering the solidus toextend ΔT. If this width ΔT is extended, casting is facilitated since afixed time can be ensured up to solidification after casting. However,an excessively large ΔT causes reduction in proof stress in alow-temperature area, causing cracking at the end of solidification, orso-called solder brittleness. Therefore, ΔT is preferably set within therange of 50 to 200° C.

C, N and O are generally included as impurities. These elements formcarbides, nitrides and oxides with metal elements in the alloy. Theseelements may be actively added since the precipitates or inclusionsthereof are effective, if fine, for strengthening the alloy,particularly, for enhancing high-temperature strength similarly to theprecipitates of metal, compounds of copper and additive elements orbetween additive elements and the like, which are described later. Forexample, O has an effect of forming oxides in order to enhance thehigh-temperature strength. This effect is easily obtained in an alloycontaining elements which easily form oxides, such as Mg, Li, Ca andrare earth elements, Al, Si and the like. However, in this case, acondition in which the solid solution O never remains must be selected.Care should be taken with residual solid solution oxygen, since it maycause, in heat treatment under hydrogen a mosphere, a so-called hydrogendisease of causing a phreatic explosion as H₂O gas and generate blisteror the like, which deteriorates the quality of the product.

When the content of each of these elements exceeds 1%, the precipitatesor inclusions thereof are coarse, deteriorating the ductility.Therefore, each content is preferably limited to 1% or less, and furtherpreferably to 0.1% or less. content of H is desirably as small aspossible, since H included as an impurity in the alloy, remains in thestate of H₂ gas, which causes rolling flaw or the like.

Be is an element that contributes to precipitation-strengthening withoutdeteriorating electric conductivity remarkably. In order to obtain theeffect, it is preferable that the content of Be is 0.1 mass % or more.However, a content exceeding 5% causes not only reduction in electricconductivity but also reduction of ductility, which deterioratesworkability for rolling or bending and the like. Therefore, thepreferable content of Be is 0.1 to 5% when it is added.

(b) The Total Number of Precipitates and Inclusions

In the copper alloy of the present invention, the relationship betweenthe total number N and the diameter X of precipitates and inclusionsthat have a diameter of not smaller than 1 μm satisfies the followingformula (1):

log N≦0.4742+17.629×exp(−0.1133×X)  (1)

wherein N means the total number of precipitates and inclusions, havinga diameter of not smaller than 1 μm, which are found in 1 mm² of thealloy; and X means the diameter in μm of the precipitates and theinclusions having diameter of not smaller than 1 μm. In the formula (1),X=1 is substituted when the measured value of the grain size of theprecipitates and the inclusions are 1.0 μm or more and less than 1.5 μm,and X=α(αis an integer of 2 or more) is substituted when the measuredvalue is “α−0.5” μm or more and less than “α+0.5” μm.

In the copper alloy of the present invention, fine precipitates ofmetal, compounds of copper and additive elements and between additiveelements can improve the strength without reducing the electricconductivity. They enhance the strength by precipitation hardening. Thedissolved Cr, Ti, and Zr are reduced by precipitation, and the electricconductivity of the copper matrix comes close to that of pure copper.

However, when these precipitates and inclusions such as metal oxides,metal carbides and metal nitrides become coarse with a diameter of 20 μmor more, the ductility deteriorates, easily causing cracking orchipping, for example, at the time of bending or punching for making aconnector. It might adversely affect fatigue characteristic and impactresistance characteristic in use. Particularly, when a coarse Ti—Crcompound is formed at the time of cooling after solidification, crackingor chipping tends to occur in the subsequent working process. Since thehardness is excessively increased in an aging treatment process, fineprecipitation of said precipitates and inclusions is inhibited, so thatthe copper alloy cannot be strengthened. Such a problem is noticeablewhen the relationship between the total number of N and the diameter Xdoes not satisfy the above formula (1).

In the present invention, therefore, an essential requirement isregulated so that the relationship between the total number of N and thediameter X satisfies the above formula (1). The total number of theprecipitates and the inclusions desirably satisfies the followingformula (2), and further preferably satisfies the following formula (3).The diameter and the total number of the precipitates and the inclusionscan be determined by using a method shown in Examples.log N≦0.4742+7.9749×exp(−0.1133×X)  (2)log N≦0.4742+6.3579×exp(−0.1133×X)  (3)

wherein N means the total number of precipitates and inclusions, havinga diameter not smaller than 1 μm which are found in 1 mm² of the alloy;and X means the diameter in μm of the precipitates and the inclusionshaving diameter not smaller than 1 μm.

-   (c) Ratio of the “Average Content Maximum Value” to the “Average    Content Minimum Value” in Micro-area of at Least One Alloy eEement.

The presence of a structure, in which areas with differentconcentrations of alloy elements are finely mingled, in the copperalloy, or the occurrence of a periodic concentration change has aneffect of facilitating acquisition of the micro-crystal grain structure,since it inhibits minute diffusion of each element and the grainboundary migration. Consequently, the strength and ductility of thecopper alloy are improved according to the so-called Hall-Petch law. Themicro-area means an area of 0.1 to 1 μm diameter, which substantiallycorresponds to an irradiation area in X-ray analysis.

The areas with different alloy element concentrations in the presentinvention are the following two types.

(1) A state basically having the same fcc structure as Cu, but havingdifferent alloy element concentrations. The lattice constant isgenerally differed in spite of the same fcc structure due to thedifferent alloy element concentrations, and also the degree of workhardening is of course differed.

(2) A state where fine precipitates are dispersed in the fcc matrix. Thedispersed state of precipitates after working and heat treatment is ofcourse differed due to the different alloy element concentrations.

The average content in the micro-area means the value in an analysisarea when narrowing to a fixed beam diameter of 1 μm or less in theX-ray analysis. The value is the average content in this area. In caseof the X-ray analysis, an analyzer having a field emission type electrongun is desirably used. A desirable analyzing means are such that have aresolution of ⅕ or less of the concentration period, and 1/10 is furtherdesirable. If the analysis area is too large during the concentrationperiod, the whole is averaged to make the concentration differencedifficult to emerge. Generally, the measurement can be performed by anX-ray analysis method with a probe diameter of about 1 μm.

It is the alloy element concentration and fine precipitates in thematrix that determines the material characteristics. Therefore, theconcentration difference in micro-area including fine precipitates isquestioned in the present invention. Accordingly, signals from coarseprecipitates or coarse inclusions of 1 μm or more are disturbancefactors. However, it is difficult to perfectly remove the coarseprecipitates or coarse inclusions from an industrial material, andtherefore it is necessary to remove these disturbing factors from thecoarse precipitates and inclusions at the time of analysis. Thefollowing procedure is therefore taken.

A line analysis is performed using of an X-ray analyzer with a probediameter of about 1 μm in order to grasp the periodic structure ofconcentration, although it is varied depending on the materials. Ananalysis method is determined so that the probe diameter is about ⅕ ofthe concentration period or less as described above. Then a sufficientline analysis length, where the period emerges about three times or moreis determined. The line analysis is performed m-times (desirably 10times or more) under this condition, and the maximum value and theminimum value of concentration are determined for each of the lineanalysis results.

M pieces each of the resulting maximum values and minimum values are cutby 20% from the larger value side and averaged. By the above-mentionedprocedure, the disturbing factors due to the signals from the coarseprecipitates and inclusions can be removed.

The concentration ratio is determined by the ratio of the maximum valuecompared to the minimum value from which the disturbance factors havebeen removed. The concentration ratio can be determined for an alloyelement, having a periodic concentration change of about 1 μm or more,without taking a concentration change of an atomic level of about 10 nmor less, such as spinodal decomposition or micro-precipitates, intoconsideration.

The reason that the ductility is improved by finely distributing alloyelements will now be described in detail. When a concentration change ofan alloy element takes place, the mechanical properties are differedbetween the high-concentration part and the low-concentration part,since the degree of solid-solution hardening of materials and thedispersed state of precipitates between them are different. Duringdeformation of such material, the relatively soft part, i.e.,low-concentration part is work-hardened first, and then the deformationof the relatively hard part, i.e., high-concentration part is started.In other words, since the work hardening is caused for a plurality oftimes as the whole material, high elongation is shown, for example, intensile deformation, and also ductility improvement is seen. Thus, in analloy where a periodic concentration change of alloy elements takesplace, high ductility advantages for bending work or the like can beexhibited while keeping the balance between electric conductivity andtensile strength.

Since the electric resistance (the inverse of electric conductivity)mainly responds to a phenomenon in which the electron transition isreduced due to the scattering of dissolved elements, and is hardlyaffected by a macro defect such as grain boundary, the electricconductivity is never reduced by the above-mentioned fine grainstructure.

This effect is noticeable when the ratio of the “average content maximumvalue” to the “average content minimum value” in the micro-area of atleast one alloy element in the matrix (hereinafter simply referred to as“concentration ratio”) is 1.5 or more. The upper limit of theconcentration ratio is not particularly determined. However, anexcessively high concentration ratio might cause adverse effects, suchthat an excessively increased difference of the electrochemicalcharacteristics which facilitates local corrosion, and in addition tothat the fcc structure possessed by the Cu alloy cannot be kept.Therefore, the concentration ratio is set preferably to 20 or less, andmore preferably to 10 or less.

(d) Grain Size

A finer grain size of the copper alloy is advantageous for enhancing thestrength, and also leads to an improvement in ductility which improvesbending workability and the like. However, when the grain size is below0.01 μm, high-temperature strength may be reduced, and if it exceeds 35μm, the ductility is reduced. Therefore, the grain size is desirably setat 0.01 to 35 μm, and further desirably to 0.05 to 30 μm, and mostdesirably to 0.1 to 25 μm.

2. Method for Producing a Copper Alloy of the Present Invention

In the copper alloy of the present invention, inclusions such as metaloxides, metal carbides and metal nitrides, which inhibit the fineprecipitation of metals, compounds of copper and additive elements andbetween additive elements, tend to formed just after the solidificationfrom the melt. It is difficult to dissolve such inclusions even if thesolution treatment at a higher temperature is performed after casting.The solution treatment at a high temperature only causes coagulation andthe coarsening of the precipitates and inclusions.

Therefore, in the method for producing the copper alloy of the presentinvention, a bloom, a slab, a billet or an ingot, obtained by meltingthe copper alloy having the above chemical composition by casting, iscooled to at least a temperature range from the bloom, the slab, thebillet or the ingot temperature just after casting to 450° C., at acooling rate of 0.5° C./s or more, whereby the relationship between thetotal number N and the diameter X of the precipitates and the inclusionshaving diameter of not smaller than 1 μm satisfies the following formula(1):log N≦0.4742+17.629×exp(−0.1133×X)  (1)

wherein N means the total number of precipitates and inclusions, whichare found in 1 mm² of the alloy; and X means the diameter in μm of theprecipitates and the inclusions having diameter of not smaller than 1μm.

After the cooling, working in a temperature range of 600° C. or lower,and a holding heat treatment for 30 seconds or more in a temperaturerange of 150 to 750° C. after this working are desirably performed. Theworking in a temperature range of 600° C. or lower and the holding heattreatment for 30 seconds or more in a temperature range of 150 to 750°C. are further desirably performed for a plurality of times. After thefinal heat treatment, the working may be further performed.

-   (a) A cooling rate at least in a temperature range from the bloom,    the slab, the billet or the ingot temperature just after casting to    450° C.: 0.5° C./s or more

The precipitates such as metals, compounds of copper and added elementsand between added compounds are formed in a temperature range of 280° C.or higher. Particularly, when the cooling rate in a temperature range,from the bloom, the slab, the billet or the ingot temperature just aftercasting to 450° C. is low, inclusions such as metal oxides, metalcarbides and metal nitrides are coarsely formed, and the diameterthereof may reach 20 μm or more, and further hundreds μm. Further, thesaid precipitates are also coarsened to 20 μm or more. In a state wheresuch coarse precipitates and inclusions are formed, not only cracking orchipping may take place in the subsequent working, but also aprecipitation hardening effect of the precipitates in an aging processis impaired, so that the alloy cannot be strengthened. Accordingly, itis needed to cool the bloom, the slab, the billet or the ingot at acooling rate of 0.5° C./s or more at least in the said temperaturerange. A higher cooling rate is more preferable. The cooling rate ispreferably 2° C./s or more, and more preferably 10° C./s or more.

-   (b) Working Temperature After Cooling: A Temperature Range of    600° C. or Lower

In the method for producing a copper alloy of the present invention, thebloom, the slab, the billet or the ingot obtained by casting is madeinto a final product, after cooling under a predetermined condition,only by a combination of working and aging heat treatment withoutpassing through a hot process, such as hot rolling or solutiontreatment.

A working such as rolling or drawing may be performed at 600° C. orlower. For example, when continuous casting is adapted, such a workingcan be performed in the cooling process after solidification. When theworking is performed in a temperature range exceeding 600° C.,precipitates such as metals, compounds of copper and additive elementsand between additive elements are coarsely formed at the time ofworking, deteriorating the ductility, impact resistance, and fatigueproperty of the final product. When the above-mentioned precipitates arecoarsened at the time of working, fine precipitates cannot be formed inthe aging treatment, resulting in an insufficient strengthening of thecopper alloy.

Since the dislocation density in working is raised more as the workingtemperature is lower, precipitates such as metals, compounds of copperand additive elements and between additive elements can become finer inthe subsequent aging treatment. Therefore, further high strength can begiven to the copper alloy. The working temperature is preferably 450° C.or lower, more preferably 250° C. or lower, and most preferably 200° C.or lower. The temperature may also be 25° C. or lower.

The working in the above temperature range is desirably performed at aworking rate (section reduction rate) of 20% or more, and more desirably50% or more. If the working is performed at such a working rate, thedislocation introduced thereby can act as precipitation nuclei at thetime of aging treatment, which leads to fine dispersion of theprecipitates and also shortens of the time required for theprecipitation, and therefore the reduction of dissolved elements harmfulto electric conductivity can be early realized.

(c) Aging Treatment Condition: Holding for 30 Seconds or More in aTemperature Range of 150 to 750° C.

The aging treatment is effective for precipitating metals, compounds ofcopper and additive elements and between additive elements in order tostrengthen the copper alloy, and also reduce dissolved elements (Cr, Ti,etc.) harmful to electric conductivity in order to improve the electricconductivity. However, at a treatment temperature below 150° C., anexcessive amount of time is required for the diffusion of theprecipitated elements, which reduces the productivity. On the otherhand, at a treatment temperature exceeding 750° C., not only theprecipitates are too coarsened to attain the strengthening by theprecipitation hardening effect, but also the ductility, impactresistance and fatigue characteristic deteriorates. Therefore, the agingtreatment is desirably performed in a temperature range of 150 to 750°C. The aging treatment temperature is desirably 200 to 750° C., furtherdesirably 250 to 650° C., and most desirably 280 to 550° C..

When the aging treatment time is less than 30 seconds, a desiredprecipitation quantity cannot be ensured even if the aging treatmenttemperature is high. When the time is longer than 72 hours, productioncost becomes higher. Therefore, the aging treatment in a temperaturerange of 150 to 750° C. is desirably performed for 30 seconds or more.The treatment time is desirably 5 minutes or more, further desirably 10minutes or more, and most desirably 15 minutes or more. The upper limitof the treatment time is not particularly limited. However, 72 hours orless is desirable from the point of the treatment cost. When the agingtreatment temperature is high, the aging processing time can beshortened.

The aging treatment is preferably performed in a reducing atmosphere, inan inert gas atmosphere, or in a vacuum of 20 Pa or less in order toprevent the generation of scales due to oxidation on the surface.Excellent plating property can also be ensured by the treatment in suchan atmosphere.

The above-mentioned working and aging treatment may be performedrepeatedly as the occasion demands. When the working and aging treatmentare repeatedly performed, a desired precipitation quantity can beobtained in a shorter time than in the case of one set treatment(working and aging treatment), and precipitates such as metals,compounds of copper and additive elements and between additive elementscan be more finely precipitated. For example, when the treatment isrepeated twice, the second aging treatment temperature is preferably setslightly lower than the first aging treatment temperature (by 20 to 70°C.). If the second aging treatment temperature is higher, theprecipitates formed in the first aging treatment are coarsened. On andafter the third aging treatment, the temperature is desirably set lowerthan the previous aging treatment temperature. The working in atemperature range of 600° C. or lower may be performed after the finalheat treatment.

(d) Others

In the method for producing the copper alloy of the present invention,conditions other than the above production conditions, for example,conditions for melting, casting and the like are not particularlylimited. These treatments may be performed as follows.

Melting is preferably performed in a non-oxidative or reducingatmosphere. If the dissolved oxygen in a molten copper is increased, theso-called hydrogen-induced blistering due to generation of steam iscaused in the subsequent process. Further, coarse oxides ofeasily-oxidizable dissolved elements such as Ti and Cr are formed, andif they are left in the final product, the ductility and fatiguecharacteristic are seriously reduced.

In order to obtain the bloom, the slab, the billet or the ingot,continuous casting is preferably adapted from the point of productivityand solidification rate. However, any other methods, which satisfy theabove-mentioned conditions, for example, an ingot method, can be used.The casting temperature is preferably 1250° C. or higher, and furtherpreferably 1350° C. or higher. At this temperature, Cr, Ti and Zr can besufficiently dissolved, and formation of inclusions such as metaloxides, metal carbide and metal nitrides, precipitates such as metals,compounds of copper and additive elements and between additive elementscan be prevented.

When the bloom, the slab or the billet is obtained by the continuouscasting, a method using graphite mold, which is generally adapted for acopper alloy is recommended from the viewpoint of lubricating property.As a mold material, a refractory material, which is hardly reactive withTi, Cr or Zr that is an essential alloy element, for example, zirconiamay be used.

EXAMPLE 1

Copper alloys, having chemical compositions shown in Tables 1 to 3 weremelted by a vacuum induction furnace, and cast in a zirconia made mold,whereby slabs 12 mm thick were obtained. Each of rare earth elements wasadded alone or in a form of misch metal. TABLE 1 Chemical Composition(mass %, Balance: Cu & Impurities) Alloy 2nd group elements No. 1stgroup elements Total Ti Zr Hf Cr 3rd group elements Total 4th groupelements Total Be  1 15Fe, 1.0Si, 0.2Sn, 1.2Al 17.4 0.05 — — — 0.5Y,0.01Nd, 0.02Ca 0.53 0.001B 0.001 —  2 10Fe, 2.5Ni, 1.0Si, 0.4Zn 13.90.49 — — — — — — — —  3 1.01Fe, 0.1Zn 1.11 1.02 — — — 0.02Mg 0.02 — — — 4 0.99Fe, 0.5Ag 1.49 1.51 — — — — — 0.01P, 0.1Bi 0.11 —  5 0.01Sn 0.011.93 — — — 0.001La 0.001 0.15Sr, 0.5Pd, 0.1Os 0.75 —  6* 5.0Zn, 15Fe,5Co, 2.0Si 27.0*  5.80* — — — 0.5Nd, 0.5Gd, 2.0Ca 3.0* 0.5B, 0.6Tc 1.1 — 7 0.2Ta, 12Co, 1.5Si 13.7 — 0.07 — — 0.2Sc, 0.2Ce 0.4 0.1Tl, 0.5Cs,0.1Po 0.7 —  8 2.5Fe, 15.5Nb, 0.1Ge 18.1 — 0.51 — — — — — — —  9 0.97Fe,0.5V, 0.3Mo 1.77 — 1.02 — — 0.01Mg, 0.1Gd 0.11 — — — 10 0.5Fe, 0.5Ta 1.0— 1.48 — — 0.01Mg 0.01 0.011P, 1.0Ba, 0.1Sb 1.111 — 11 1.01Fe, 0.1W,0.1Ag 1.21 — 2.01 — — — — 0.012B, 0.1Re, 0.1Tc 0.212 — 12* 1.5W, 0.5Al,0.5Ag 2.5 — 6.10* — — 0.1La, 0.01Ca 0.11 0.2Sb 0.2 — 13 0.4Mo, 1.0Co,15Fe, 0.4Se 16.8 — — 0.01 — 0.1La, 0.01Mg, 0.001Li 0.111 0.1In, 0.5Pd,0.1Ga 0.7 — 14 1.0Fe, 0.5Si, 1.0Nb 2.5 — — 0.52 — — — — — — 15 0.98Fe,0.2Mo, 0.4Zn 1.58 — — 0.99 — 0.01Li 0.01 — — — 16 0.99Fe 0.99 — — 1.48 —0.01Ca 0.01 0.010P, 0.02B 0.03 — 17 0.4Si, 0.3Sn, 1.2V 1.9 — — 2.01 — —— 0.1Sr, 0.2Re 0.3 — 18* 0.5Fe, 1.0Co, 0.4Sn 1.9 — — 6.20* — 0.01Sc,0.1Mg 0.11 0.9Bi, 0.1P 1.0 — 19 10V, 2.2Co, 0.4Ta, 0.4Mn, 1.0Sn 14.0 — —— 0.05 0.01La 0.01 0.1Rh, 0.01P 0.11 — 20 2.01Fe, 0.2Mo, 0.5Nb 2.71 — —— 0.50 — — — — — 21 1.0Ni, 0.5Si, 0.4Sn 1.9 — — — 0.99 0.02Ca 0.02 — — —22 0.99Fe 0.99 — — — 1.49 0.01Li, 0.03Ca 0.04 0.011P, 1.0Bi 1.011 — 231.0Fe, 0.5Sn 1.5 — — — 1.99 — — 0.01B, 0.5Ba, 0.5Sb 1.01 — 24 12V, 15Fe,0.5Mo, 1.0Si, 1.0Sn 29.5* — — — 6.50* 0.1Sc, 0.01Mg 0.11 0.1Au, 0.01Po,0.1Cs 0.21 — 25* 0.99Co, 1.02Fe, 0.4Sn 2.41 1.45 — — — 0.5Ca, 0.8Li,1.5Mg 2.8* 0.001B 0.001 —*Out of the range regulated by the present invention.

TABLE 2 Chemical Composition (mass %, Balance: Cu & Impurities) Alloy2nd group elements No. 1st group elements Total Ti Zr Hf Cr 3rd groupelements Total 4th group elements Total Be 26 1.01Nb 1.01 1.32 — — — — —— — — 27 0.99Co 0.99 1.22 — — — 0.01Mg 0.01 — — — 28 0.98Fe 0.98 1.52 —— — 0.01Mg 0.01 0.008P, 0.01B 0.018 — 29 0.5V, 0.2Ag 0.7 1.98 — — — — —0.009Bi 0.009 — 30* 12.5Ni, 5.1Si, 5.6Nb 23.2* 1.55 — — — 1.5Mg, 1.0La2.5* 0.5In, 1.5Ba, 1.0Os 3.0* — 31 0.95Co 0.95 — 1.11 — — — — 0.001S0.001 — 32 1.00Nb 1.00 — 1.48 — — 0.1La, 1.5Ca 1.6 — — — 33 0.99Fe 0.99— 1.49 — — 0.1Mg, 0.5Nd, 0.8Li 1.4 0.01Cs, 0.03Bi 0.04 — 34 0.98Co 0.98— 1.52 — — — — 0.01P 0.01 — 35* 1.1V 1.1 — 1.32 — — 0.1La, 1.5Rh, 2.0Ce3.6* 1.0Ba, 1.3Po, 2.0Rh 4.3* — 36 0.99V, 0.24Si 1.23 — — 1.52 — — —0.01Bi, 0.02Ba, 0.001P 0.031 — 37 1.01Co, 2.3Fe, 0.4Sn 3.71 — — 1.48 — —— — — — 38 1.1Nb, 0.3Sn, 1.2Ni 2.6 — — 1.22 — 0.01Li, 0.03Gd 0.04 — — —39* 10.0Co, 10.2Fe, 0.5Si, 26.0* — — 1.38 — 0.01Ca, 0.1Sc 0.11 0.009P0.009 — 4.3W, 1.0Mo 40 0.99Co, 0.1Si 1.01 — — — 1.32 — — — — — 41*0.99Nb, 0.1Ge 1.01 — — — 1.42 0.1Ce, 0.01Y 0.11 0.5Sb, 1.5Ba, 1.0Bi 3.0*— 42* 1.01V, 0.1Al, 0.2Ni 1.31 — — — 1.48 0.01Mg 0.01 1.5Rb, 1.0Pd 2.5*— 43 1.00Mo, 0.4Zn 1.40 — — — 1.35 — — 0.012P 0.012 — 44 1.54Co, 0.8Al2.34 — — — — 0.01Nd, 0.05Sc 0.06 — — — 45 0.99Nb, 0.4Mn 1.39 — — — — — —0.01B 0.01 — 46 1.52Fe, 0.4Te 1.92 — — — — 0.01Mg, 0.05Y, 0.001Li 0.0610.011Pd, 0.1Re 0.11 — 47 2.01Fe, 0.4Zn 2.41 — — — — — — — — — 48* 8.0Nb,4.0Si, 5.2Ta 17.2 — — — — 0.7La, 0.5Ca, 1.2Sc 2.4* — — — 49 14Ni, 4Si,1Ag 19 — — — — 0.01Nd, 0.05Y 0.06 — — — 50 5.2Mo, 3.1V 8.3 — — — — — —0.01P, 0.1Ba 0.11 —*Out of the range regulated by the present invention.

TABLE 3 Chemical Composition (mass %, Balance: Cu & Impurities) Alloy2nd group elements No. 1st group elements Total Ti Zr Hf Cr 3rd groupelements Total 4th group elements Total Be 51 10.1W, 4.2Ge 14.3 — — — —0.1Ce, 0.01La 0.11 0.1Sr, 0.1Os 0.2 — 52 2.5Co 2.5 — — — — 0.01Mg 0.01 —— — 53 1.54Fe 1.54 — — — — — — 0.001B 0.001 — 54 1.24V 1.24 — — — —0.001Li 0.001 0.01Bi 0.01 — 55* 10.2Fe, 7.8Co, 3.4Zn, 28.4* — — — — — —— — — 3.2Al, 3.8W 56 0.5Fe, 0.5Co, 0.5Ag 1.5 3.00 — — — — — 0.1Ba,0.01Os 0.11 — 57 0.4Sn, 1.0Fe 1.4 4.00 — — — 0.1Sc, 0.1Ca 0.2 — — — 580.25Ta, 0.3Nb 0.55 — 2.50 — — 0.01Nd, 0.1La 0.11 0.1Pd, 0.05Bi 0.15 — 590.5Mo, 0.1Fe 0.6 — 4.00 — — — — 0.01P, 0.1Re 0.11 — 60 0.5Fe, 0.1Si,0.2Sn 0.8 1.50 — — — 0.2Ca 0.2 0.01P, 0.1S 0.11 — 61 0.6Ag, 4.0Co 4.6 —— — — — — — — 0.4 62 1.0Zn, 1.0Ag, 3.0Nb 5.0 — — — — 0.5Mg, 0.1Gd 0.6 —— 2.1 63 2.0Fe, 0.5Ta 2.5 — — — — — — 0.1P, 0.01B 0.11 0.5 64 0.4Ag 0.4— — — 2.50 — — — — 2.1 65 1.0Sn, 2.5Fe, 3.0Se 6.5 — — — — 0.01Nd 0.010.25B, 0.001Tl 0.251 0.6 66 2.0Sn, 0.1Al, 0.1Si 2.2 — 0.01 — 2.50 0.1Y,0.5Sc 0.6 0.5Sb 0.5 2.3 67 0.2Sn, 0.4Te 0.6 0.50 — — — 0.1Ca 0.1 0.01P,0.1B, 0.001Ga 0.111 2.8 68 0.1Ag, 0.3Fe, 0.5Mo, 0.2Se 1.1 0.20 0.20 — —— — — — 0.6 69 0.5Sn, 0.1Ag 0.6 1.00 2.00 — — — — 0.3B, 0.1Re, 0.2Rh 0.62.8 70 0.5Ta 0.5 — 0.30 — — 0.1Gd 0.1 — — 2.6*Out of the range regulated by the present invention.

Each of the resulting slabs was cooled from a temperature between 950°C. and 450° C., which is the temperature just after casting (thetemperature just after taken out of the mold), by water spray. Thetemperature change of the mold in a predetermined place was measured bya thermocouple buried in the mold, and the surface temperature of theslab, after leaving the mold, was measured in several areas by a contacttype thermometer. The average cooling rate, in the temperature range to450° C., of the slab surface was calculated by using the above measuringresults and a thermal conduction analysis. In another small scaleexperiment, the solidification starting point was determined by using0.2 g of a melt of each alloy, and thermally analyzing it duringcontinuous cooling at a predetermined rate.

A plate for subsequent rolling with 10 mm thickness ×8 Omm width ×150 mmlength was prepared from each resulting slab by cutting and machining.For comparison, a part of the plate was subjected to a solution heattreatment at 950° C.. The plates were rolled to 2 mm thick sheets by areduction of 80% at a room temperature (first rolling), and furthersubjected to aging treatment under a predetermined condition (firstaging). A part of the specimens were further subjected to rolling by areduction of 95% into 0.1 mm thickness at room temperature (secondrolling), and then subjected to aging treatment under a predeterminedcondition (second aging). The production conditions thereof are shown inTables 4 to 7.

For the thus-produced specimens, the diameter and the total number perunit area of the precipitates and the inclusions, tensile strength,electric conductivity and bending workability were measured by thefollowing methods. These results are also shown in Tables 4 to 7.

≦Total Number of Precipitates and Inclusions>

A section parallel to the rolling plane and that perpendicular to thetransverse direction of each specimen ware polish-finished, and a visualfield of 1mm×1mm was observed by an optical microscope at 100-foldmagnification after being etched with an ammonia aqueous solution.Thereafter, the long diameter (the length of a straight line which canbe drawn longest within a grain, without contacting the grain boundaryhalfway) of the precipitates and the inclusions was measured, and theresulting value is determined as grain diameter. When the measured valueof the grain diameter of the precipitates and the inclusions is 1.0 μmor more and less than 1.5 μm, X=1 is substituted to the formula (1), andwhen the measured value is “α−0.5” μm or more and less than “α+0.5” μm,X=α(αis an integer of 2 or more) can be substituted. Further, the totalnumber n₁ is calculated by taking one crossing of the frame line of avisual field of 1mm×1 mm as ½ and one located within the frame line as 1for every grain diameter, and an average “N/10” of the number of theprecipitates and the inclusions N (=n₁+n₂ +. . . +n₁₀) in an optionallyselected 10 visual fields is defined as the total number of theprecipitates and the inclusions for each grain diameter of the sample.

≦Content Ratio>

A section of the alloy was polished and analyzed at random 10 times fora length of 50 μm by an X-ray analysis at 2000-fold magnification inorder to determine the maximum values and minimum values of each alloycontent in the respective line analyses. Averages of the maximum valueand the minimum value were determined for eight values each afterremoving the two larger ones respectively from the determined maximumvalues and minimum values, and the ratio thereof was calculated as thecontent ratio.

≦Tensile Strength>

A specimen 13B regulated in JIS Z 2201 was prepared from theabove-mentioned specimen so that the tensile direction is parallel tothe rolling direction, and according to the method regulated in JIS Z2241, tensile strength [TS (MPa)] at room temperature (25° C.) thereofwas determined.

≦Electric Conductivity>

A specimen of 10 mm width ×60 mm length was prepared from theabove-mentioned specimen so that the longitudinal direction is parallelto the rolling direction, and the potential difference between both endsof the specimen was measured by applying current in the longitudinaldirection of the specimen, and the electric resistance was determinedtherefrom by a 4-terminal method. Successively, the electric resistance(resistivity) per unit volume was calculated from the volume of thespecimen measured by a micrometer, and the electric conductivity [IACS(%)] was determined from the ratio to resistivity 1.72 μΩ•cm of astandard sample obtained by annealing a polycrystalline pure copper.

≦Bending Workability>

A plurality of specimens of 10 mm width ×60 mm length were prepared fromthe above-mentioned specimen, and a 90° C. bending test was carried outwhile changing the curvature radius (inside diameter) of the bent part.After the test the bent parts of the specimens were observed from theouter diameter side by use of an optical microscope. A minimum curvatureradius free from cracking was taken as R, and the ratio B(=R/t) of R tothe thickness t of specimen was determined. TABLE 4 Production ConditionCooling 1st Rolling 1st Heat Treatment 2nd Rolling 2nd Heat TreatmentAlloy Rate Temp. Thickness Temp. Temp. Thickness Temp. Division No. (°C./s) (° C.) (mm) (° C.) Time (° C.) (mm) (° C.) Time Examples of The 11 9 25 2.0 400 2 h 25 0.1 350 10 h Present Invention 2 2 10 25 2.0 400 2h 25 0.1 350 10 h 3 3 10 25 2.0 400 2 h 25 0.1 350 10 h 4 4 11 25 2.0400 2 h 25 0.1 350 10 h 5 5 11 25 2.0 400 3 h 25 0.1 350 10 h 6 7 10 252.1 400 2 h 25 0.1 350 10 h 7 8 10 25 1.9 400 2 h 25 0.1 350 10 h 8 9 1125 2.0 400 2 h 25 0.1 350 10 h 9 10 10 25 2.0 400 2 h 25 0.1 350 10 h 1011 10 25 2.0 400 3 h 25 0.1 350 10 h 11 13 10 25 2.0 400 2 h 25 0.1 35010 h 12 14 10 25 1.9 400 2 h 25 0.1 350 10 h 13 15 11 25 2.0 400 2 h 250.1 350 10 h 14 16 9 25 1.9 400 2 h 25 0.1 350 10 h 15 17 9 25 1.9 400 3h 25 0.1 350 10 h 16 19 11 25 2.0 400 2 h 25 0.1 350 10 h 17 20 11 252.0 400 2 h 25 0.1 350 10 h 18 21 10 25 2.0 400 2 h 25 0.1 350 10 h 1922 10 25 2.0 400 2 h 25 0.1 350 10 h 20 23 10 25 2.0 400 2 h 25 0.1 35010 h 21 24 10 25 2.0 400 2 h 25 0.1 350 10 h 22 26 10 25 2.0 400 2 h 250.1 350 10 h 23 27 10 25 2.0 400 2 h 25 0.1 350 10 h 24 28 9 25 2.0 4002 h 25 0.1 350 10 h 25 29 11 25 2.0 400 2 h 25 0.1 350 10 hCharacteristics Grain Tensile Bending Workability Size StrengthConductivity B Division {circle around (1)} {circle around (2)} (μm)(MPa) (%) (R/t) Evaluation Examples of The 1 Δ 10.5(Fe) 30 905 23 2 ◯Present Invention 2 ⊚ 10(Fe), 1.5(Si) 14 1020 26 2 ◯ 3 ⊚ 3.2(Ti) 10 116917 2 ◯ 4 ⊚ 2.5(Ti) 8 1301 10 3 ◯ 5 ◯ 3.1(Ti) 0.1 1409 6 5 ◯ 6 Δ 2.4(Si)20 910 21 2 ◯ 7 ⊚ 12(Nb), 2.5(Fe) 25 1019 26 2 ◯ 8 ⊚ 1.8(Zr) 15 1173 163 ◯ 9 ⊚ 2.5(Zr) 8 1295 10 5 ◯ 10 ◯ 5.6(Zr) 1 1439 4 5 ◯ 11 Δ 5.2(Fe) 30890 25 2 ◯ 12 ⊚ 1.5(Nb), 1.2(Fe) 16 1050 25 2 ◯ 13 ⊚ 1.8(Fe), 1.5(Zn) 121172 17 3 ◯ 14 ⊚ 1.8(Hf) 5 1293 11 5 ◯ 15 ◯ 2.8(Hf) 0.2 1439 5 5 ◯ 16 Δ12.5(V) 16 900 25 1 ◯ 17 ⊚ 3.9(Ti) 33 782 54 1 ◯ 18 ⊚ 2.3(Ni), 1.5(Si)35 780 55 1 ◯ 19 ⊚ 1.8(Fe) 28 865 40 2 ◯ 20 ⊚ 1.9(Fe) 19 954 30 2 ◯ 21 ⊚11.9(V) 12 1000 22 2 ◯ 22 ⊚ 5.9(Ti) 10 1230 15 2 ◯ 23 ⊚ 3.5(Ti), 1.5(Co)9 1209 18 3 ◯ 24 ⊚ 3.8(Ti), 1.6(Fe) 10 1290 10 3 ◯ 25 ◯ 5.2(Ti), 1.5(Ag)0.5 1405 6 5 ◯“h” in “Time” means hour.“Δ”, “◯” and “⊚” in {circle around (1)} mean that formulas (1), (2) and(3) are satisfied, respectively.{circle around (2)} means “content maximum value/content minimum value”.Object element is shown in parentheses.“◯” in “Bending Workability” means that formula (b) is satisfied.

TABLE 5 Production Condition Cooling 1st Rolling 1st Heat Treatment 2ndRolling 2nd Heat Treatment Alloy Rate Temp. Thickness Temp. Temp.Thickness Temp. Division No. (° C./s) (° C.) (mm) (° C.) Time (° C.)(mm) (° C.) Time Examples of The 26 31 9 25 2.0 400 2 h 25 0.1 350 10 hPresent Invention 27 32 10 25 1.9 400 2 h 25 0.1 350 10 h 28 33 10 252.0 400 2 h 25 0.1 350 10 h 29 34 10 25 2.0 400 2 h 25 0.1 350 10 h 3036 11 25 2.0 400 2 h 25 0.1 350 10 h 31 37 10 25 2.0 400 2 h 25 0.1 35010 h 32 38 9 25 1.9 400 2 h 25 0.1 350 10 h 33 40 10 25 2.0 400 2 h 250.1 350 10 h 34 43 9 25 2.0 400 2 h 25 0.1 350 10 h 35 44 10 25 2.0 4002 h 25 0.1 350 10 h 36 45 10 25 2.0 400 2 h 25 0.1 350 10 h 37 46 9 252.0 400 2 h 25 0.1 350 10 h 38 47 10 25 2.0 400 2 h 25 0.1 350 10 h 3949 10 25 2.0 400 2 h 25 0.1 350 10 h 40 50 9 25 2.0 400 2 h 25 0.1 35010 h 41 51 9 25 2.0 400 2 h 25 0.1 350 10 h 42 52 10 25 2.0 400 2 h 250.1 350 10 h 43 53 11 25 2.0 400 2 h 25 0.1 350 10 h 44 54 11 25 2.0 4002 h 25 0.1 350 10 h 45 56 9 25 2.0 400 2 h 25 0.1 350 10 h 46 57 10 252.0 400 2 h 25 0.1 350 10 h 47 58 9 25 2.0 400 2 h 25 0.1 350 10 h 48 599 25 2.0 400 2 h 25 0.1 350 10 h 49 60 10 25 2.0 400 2 h 25 0.1 350 10 h50 61 9 25 2.0 400 2 h 25 0.1 350  8 h Characteristics Grain TensileBending Workability Size Strength Conductivity B Division {circle around(1)} {circle around (2)} (μm) (MPa) (%) (R/t) Evaluation Examples of The26 ⊚ 1.7(Zr) 10 1240 15 2 ◯ Present Invention 27 ⊚ 2.1(Zr) 2 1302 10 3 ◯28 ⊚ 2.2(Zr) 4 1298 11 2 ◯ 29 ⊚ 2.5(Zr) 2 1300 10 3 ◯ 30 ⊚ 2.0(Zr) 21290 10 3 ◯ 31 ⊚ 13.0(Hf) 5 1230 15 3 ◯ 32 ⊚ 2.9(Hf) 12 1190 15 2 ◯ 33 ⊚2.5(Hf) 28 800 60 1 ◯ 34 Δ 3.5(Cr) 27 815 30 1 ◯ 35 ⊚ 5.2(Co), 1.5(Al)15 1005 35 1 ◯ 36 Δ 1.5(Nb) 25 836 26 1 ◯ 37 Δ 12.6(Fe) 24 928 18 1 ◯ 38⊚ 3.2(Fe) 12 1014 21 2 ◯ 39 Δ 5.2(Ni), 2.4(Si) 8 1220 10 3 ◯ 40 ⊚15.2(Mo), 7.8(V) 12 1198 26 2 ◯ 41 Δ 21(W), 1.8(Ge) 2 1320 5 4 ◯ 42 ⊚5.8(Co) 10 1030 29 3 ◯ 43 ⊚ 2.8(Fe) 20 862 40 1 ◯ 44 ⊚ 5.2(Co), 2.5(Al)21 810 49 1 ◯ 45 ⊚ 5.2(Ti) 1 1310 12 4 ◯ 46 ◯ 10.2(Ti) 0.5 1456 8 5 ◯ 47◯ 5.2(Zr) 0.1 1325 15 4 ◯ 48 ◯ 8.2(Zr) 0.3 1485 6 5 ◯ 49 ◯ 3.0(Ti) 51100 23 2 ◯ 50 ⊚ 3.2(Co) 20 820 40 1 ◯“h” in “Time” means hour.“Δ”, “◯” and “⊚” in {circle around (1)} mean that formulas (1), (2) and(3) are satisfied, respectively.{circle around (2)} means “content maximum value/content minimum value”.Object element is shown in parentheses.“◯” in “Bending Workability” means that formula (b) is satisfied.

TABLE 6 Production Condition Cooling 1st Rolling 1st Heat Treatment 2ndRolling 2nd Heat Treatment 3rd Rolling Alloy Rate Temp. Thickness Temp.Temp. Thickness Temp. Temp. Thickness Division No. (° C./s) (° C.) (mm)(° C.) Time (° C.) (mm) (° C.) Time (° C.) (mm)

51 62 10 25 2.0 400 2 h 25 0.1 350   8 h — —

52 63 10 25 2.0 400 2 h 25 0.1 350   8 h — —

53 64 10 25 2.0 400 2 h 25 0.1 350   8 h — —

54 65 10 25 2.0 400 2 h 25 0.1 350   8 h — — 55 66 10 25 2.0 400 2 h 250.1 350   8 h — — 56 67 10 25 2.0 400 2 h 25 0.1 350   8 h — — 57 68 1025 2.0 400 2 h 25 0.1 350   8 h — — 58 69 10 25 2.0 400 2 h 25 0.1 350  8 h — — 59 70 10 25 2.0 400 2 h 25 0.1 350   8 h — — 60 3 10 580 3.0 —— 25 1.0 450 1.5 h 25 0.1 61 3 10 250 3.0 700 0.5 h   25 1.0 450 1.5 h25 0.1 62 3 10 580 3.0 600 1 h 25 1.0 450 1.5 h 25 0.1 63 3 10 250 3.0 —— 25 1.0 450 1.5 h 25 0.1 64 4 10 500 3.0 — — 25 1.0 450 1.5 h 25 0.1 654 10 200 3.0 700 0.5 h   25 1.0 450 1.5 h 25 0.1 66 4 10 500 3.0 600 1 h25 1.0 450 1.5 h 25 0.1 67 4 10 250 3.0 — — 25 1.0 450 1.5 h 25 0.1Production Condition Characteristics 3rd Heat Treatment Grain TensileBending Workability Temp. Size Strength Conductivity B Division (° C.)Time {circle around (1)} {circle around (2)} (μm) (MPa) (%) (R/t)Evaluation

51 — — ⊚ 10.2(Nb), 1.5(Zn) 15 1160 17 2 ◯

52 — — ⊚ 2.5(Fe) 25 840 40 1 ◯

53 — — ⊚ 5.9(Cr) 12 1156 17 3 ◯

54 — — ⊚ 4.8(Fe) 22 870 38 1 ◯ 55 — — ⊚ 1.5(Sn) 3 1200 16 2 ◯ 56 — — ⊚1.5(Be) 0.5 1350 14 4 ◯ 57 — — ⊚ 1.5(Be), 1.5(Fe) 14 1000 29 1 ◯ 58 — —◯ 1.8(Zr) 0.01 1530 12 5 ◯ 59 — — ◯ 5.4(Be) 0.05 1500 12 5 ◯ 60 350 5 h⊚ 2.5(Ti) 15 1040 20 1 ◯ 61 350 5 h ⊚ 2.3(Ti) 7 1050 21 1 ◯ 62 350 5 h ⊚2.5(Ti) 6 1060 22 1 ◯ 63 350 5 h ⊚ 3.0(Ti) 13 1100 18 1 ◯ 64 350 5 h ⊚2.7(Ti) 12 1090 12 1 ◯ 65 350 5 h ⊚ 2.5(Ti) 6 1110 13 1 ◯ 66 350 5 h ⊚2.8(Ti) 5 1100 11 1 ◯ 67 350 5 h ⊚ 3.2(Ti) 12 1150 14 1 ◯“h” in “Time” means hour.“◯” and “⊚” in {circle around (1)} mean that formulas (1), (2) and (3)are satisfied, respectively.{circle around (2)} means “content maximum value/content minimum value”.Object element is shown in parentheses.“◯” in “Bending Workability” means that formula (b) is satisfied.

TABLE 7 Production Condition Cooling 1st Rolling 1st Heat Treatment 2ndRolling 2nd Heat Treatment Alloy Rate Temp. Thickness Temp. Temp.Thickness Temp. Division No. (° C./s) (° C.) (mm) (° C.) Time (° C.)(mm) (° C.) Time Comparative 1  6* 11 25 2.0 — — — — — — Examples 2 12*10 25 2.0 — — — — — — 3 18* 10 25 1.9 — — — — — — 4 25* 10 25 1.9 400 2h 25 0.1 350 10 h 5 26 10 25 2.0 400 2 h 25 0.1 350 10 h 6 30* 10 25 2.0400 2 h 25 0.1 350 10 h 7 33 0.3* 25 2.0 400 2 h 25 0.1 350 10 h 8 33 10800* 2.0 400 2 h 25 0.1 — — 9 34 10 25 2.0 400 2 h 25 0.1 350 10 h 1035* 10 25 2.0 400 2 h 25 0.1 350 10 h 11 37 10 25 2.0 400 2 h 25 0.1 35010 h 12 39* 10 25 2.0 400 2 h 25 0.1 350 10 h 13 41* 9 25 1.9 400 2 h 250.1 350 10 h 14 42* 9 25 2.0 400 2 h 25 0.1 350 10 h 15 43 9 25 2.0 4002 h 25 0.1 350 10 h 16 48* 10 25 2.0 400 2 h 25 0.1 350 10 h 17 55* 1025 2.0 — — — — — — Characteristics Grain Tensile Bending WorkabilitySize Strength Conductivity B Division {circle around (1)} {circle around(2)} (μm) (MPa) (%) (R/t) Evaluation Comparative 1 — — — — — — —Examples 2 — — — — — — — 3 — — — — — — — 4 X —  9 1250  5 6 X 5 X0.1(Ti) 25  750 25 6 X 6 X —  3 1310  2 7 X 7 X —  4  720 20 5 X 8 — — —— — — — 9 X 0.05(Zr) 32  720 34 5 X 10 X —  8 1110  8 5 X 11 X 0.11(Hf)28  690 38 4 X 12 X — 10 1210  5 6 X 13 X — 26  820 22 4 X 14 X — 26 873 20 4 X 15 X 0.9(Mo) 35  692 46 5 X 16 X — 10 1200  2 6 X 17 — — — —— — —“h” in “Time” means hour.“X” in {circle around (1)} means that formulas (1), (2) and (3) are notsatisfied.{circle around (2)} means “content maximum value/content minimum value”.Object element is shown in parentheses.“X” in “Bending Workability” means that formula (b) is not satisfied.

In the “Evaluation” column of bending workability of the tables, “O”shows those satisfying B≦2.0 in plate materials having tensile strengthTS of 800 MPa or less and those satisfying the following formula (b) inplate materials having tensile strength TS exceeding 800 MPa, and “×”shows those that are not satisfactory.B≦41.2686−39.4583 ×exp [−{(TS−615.675)/2358.08}²]  (b)

FIG. 2 is a graph showing the relationship between tensile strength andelectric conductivity in each example. As shown in Tables 4 to 7 andFIG. 2, regarding the chemical composition, the content ratio and thetotal number of the precipitates and the inclusions are within theranges regulated by the present invention in Inventive Examples 1 to 67and the tensile strength and the electric conductivity satisfied theabove-mentioned formula (a). Accordingly, it can be said that thebalance between electric conductivity and tensile strength of thesealloys are of a level equal to or higher than that of the Be-addedcopper alloy. Thus, the copper alloy of the present invention is foundto be rich in variations of tensile strength and electric conductivity.In Inventive Examples 1, 6, 11, 16, 34, 36, 37, 39, 41, 64, 65 and 66,the addition quantity and/or manufacturing condition were minutelyadjusted with the same component system. It can be said that thesealloys have a relationship between tensile strength and electricconductivity as shown by “Δ” in FIG. 2, and also have thecharacteristics of the conventionally known copper alloy. Further, thebending property was also satisfactory.

On the other hand, Comparative Examples 1 to 4, 6, 10, 12 to 14, 16 and17 were inferior in bending workability and electric conductivitybecause the content of any one of alloying elements is out of the rangeregulated by the present invention. For Comparative Examples 1 to 3 and17, the characteristics could not be evaluated since edge cracking inthe second rolling was too serious to collect the samples. ComparativeExamples 5, 9, 11 and 15, which were subjected to solution treatment at950° C., were inferior in tensile strength and bending workability.

EXAMPLE 2

In order to evaluate the application to the safety tools, samples wereprepared by the following method, and evaluated for wear resistance(Vickers hardness) and spark resistance.

Alloys having chemical compositions shown in Table 8 were melted in ahigh frequency furnace in the atmosphere, and were cast by the Durvilleprocess. Each bloom was produced by holding a metallic mold 1 in a stateas shown in FIG. 3C (a), pouring a melt of about 1300° C. into themetallic mold 1 while ensuring a reducing aμmosphere by charcoal powder,then tilting the mold as shown in FIG. 3C (b), and solidifying the meltin a state shown in FIG. 3 (c). The metallic mold 1 is made of cast ironwith a thickness of 50 mm, and has a pipe arrangement with a coolinghole bored in the inner part so that air cooling can be performed. Thebloom was made to a wedge shape having a bottom section of 30×300 mm, anupper section of 50×400 mm, and a height of 700 mm so as to facilitatethe pouring of the melt.

A part up to 300 mm from the lower end of the resulting bloom wasprepared followed by surface-polishing, and then subjected to coldrolling (30→10 mm) and heat treatment (375° C.×16h), whereby a plate 10mm thick was obtained. Such a plate was examined for the total number ofthe precipitates and the inclusions, tensile strength, electricconductivity, and bending workability by the above-mentioned method and,further, examined for wear resistance, thermal conductivity and sparkgeneration resistance by the method described below. The results areshown in Table 8.

≦Wear Resistance>

A specimen of 10 mm width×10 mm length was prepared from each specimen,a section vertical to the rolled surface and parallel to the rollingdirection was polish-finished, and the Vickers hardness at 25° C. andload 9.8N thereof was measured by the method regulated in JIS Z 2244.

≦Thermal Conductivity>

The thermal conductivity [TC (W/m·K)] was determined by the use of theelectric conductivity [IACS(%)] from the formula described in FIG. 1,i.e.,“TC=14.804+3.8172×IACS”.<Spark Generation Resistance>

A spark test according to the method regulated in JIS G 0566 wasperformed by use of a table grinder having a rotating speed of 12,000rpm, and the spark generation was visually confirmed.

The average cooling rate to 450° C. based on the liquidus induced by theheat conduction calculation with the temperature measured by inserting athermocouple to a position of 5 mm under the mold inner wall surface ina position 100 mm from the bottom, was determined to be 10° C./s. TABLE8 Bending Chemical Composition Grain Tensile Workability Wear ThermalSpark (mass %, Balance: Cu & Impurities) Size Strength Conductivity BResistance Conductivity Generation Division Hf Ti Zr Sn Mg P {circlearound (1)} (μm) (MPa) (%) (R/t) Evaluation (Hv) (W/m · K) ResistanceExamples 68 — — 1.0  0.5 0.01 0.01 ⊚ 25 1110 32 2 ◯ 342 137 Non of The69 — 1.5  — 0.4 — 0.05 ⊚ 12 1058 29 2 ◯ 327 126 Non Present 70 2.0 — —1.2 0.1 — ⊚ 20 998 35 2 ◯ 310 148 Non Invention Com- 18 — 5.4* — — 0.0010.1  X 2 1402 1 6 X 426 19 Generated parative Examples 19 — — 6.0* 1.50.1 — X 1 1395 1 6 X 424 19 Generated“⊚” in {circle around (1)} means that formula (3) are satisfied, “X”means that formulas (1), (2) and (3) are not satisfied respectively.“◯” in “Bending Workability” means that formula (b) is satisfied. “X”means that formula (b) is not satisfied.

As shown in Table 8, no spark was observed with satisfactory wearresistance and high thermal conductivity in Inventive Examples 68 to 70.On the other hand, sparks were observed with low thermal conductivity inComparative Examples 18 and 19, since they did not satisfy the chemicalcomposition regulated by the present invention and the relationshipshown by formula (1).

Industrial Applicability

According to the present invention, a copper alloy that has wide productvariations, and is excellent in high-temperature strength andworkability, and also excellent in the performances required for safetytool materials, or thermal conductivity, wear resistance and sparkgeneration resistance, and a method for producing the same can beprovided.

Brief Description of the Drawings

FIG. 1 A graph showing the relationship between the electricconductivity and thermal conductivity;

FIG. 2 A graph showing the relationship between the tensile strength andthe electric conductivity of each of examples.

FIG. 3 A schematic view showing a casting method by the Durvilleprocess.

EXPLANATION OF LETTERS

-   1: metallic mold

1. A copper alloy characterized in that the alloy consists of, by mass%, one or more elements selected from Zn, Sn, Ag, Mn, Fe, Co, Al, Ni,Si, Mo, V, Nb, Ta, W, Ge, Te and Se of 0.1 to 20% respectively or intotal, and the balance Cu and impurities; and the alloy satisfies thefollowing formula (1):log N≦0.4742+17.629 exp(−0.1133 X)  (1)wherein N means the total numberof precipitates and inclusions, having a diameter of not smaller than 1μm, which are found in 1 mm² of the alloy; and X means the diameter inμm of the precipitates and the inclusions having a diameter of notsmaller than 1 μm.
 2. A copper alloy characterized in that the alloyconsists of, by mass %, any one element selected from Ti of 0.01 to 5%,Zr of 0.01 to 5% and Hf of 0.01 to 5%, and one or more elements selectedfrom Zn, Sn, Ag, Mn, Fe, Co, Al, Ni, Si, Mo, V, Nb, Ta, W, Ge, Te and Seof 0.01 to 20% respectively or in total, and the balance Cu andimpurities; and the alloy satisfies the following formula (1):log N≦0.4742+17.629 exp(−0.1133 X)  (1)wherein N means the total numberof precipitates and inclusions, having a diameter of not smaller than 1μm, which are found in 1 mm² of the alloy; and X means the diameter inμm of the precipitates and the inclusions having a diameter of notsmaller than 1 μm.
 3. A copper alloy characterized in that the alloyconsists of, in mass %, Cr of 0.01 to 5%, and one or more elementsselected from Zn, Sn, Ag, Mn, Fe, Co, Al, Ni, Si, Mo, V, Nb, Ta, W, Ge,Te and Se of 0.01 to 20% respectively or in total, and the balance Cuand impurities; and the alloy satisfies the following formula (1):log N≦0.4742+17.629 exp(−0.1133 X)  (1) wherein N means the total numberof precipitates and inclusions, having a diameter of not smaller than 1μm, which are found in 1 mm² of the alloy; and X means the diameter inμm of the precipitates and the inclusions having a diameter of notsmaller than 1 μm.
 4. A copper alloy according to claim 1, characterizedin that the alloy contains, instead of a part of Cu, one or moreelements selected from Mg, Li, Ca and rare earth elements of 0.001 to 2mass % respectively or in total.
 5. A copper alloy according to claim 1,characterized in that the alloy contains, instead of a part of Cu, oneor more elements selected from P, B, Bi, TI, Rb, Cs, Sr, Ba, Tc, Re, Os,Rh, In, Pd, Po, Sb, Au, Ga, S, Cd, As and Pb of 0.001 to 3 mass %respectively or in total.
 6. A copper alloy according to claim 1,characterized in that the alloy contains, instead of a part of Cu, Be of0.1 to 5 mass %.
 7. A copper alloy according to claim 1, wherein theratio of the “maximum value of an average content” and the “minimumvalue of an average content” of at least one alloy element in a microarea is not smaller than 1.5.
 8. A copper alloy according to claim 1,wherein the grain diameter is 0.01 to 35 μm.
 9. A method for producing acopper alloy, comprising cooling a bloom, a slab, a billet or an ingotobtained by melting a copper alloy having a chemical compositiondescribed in claim 1 followed by cooling in at least a temperature rangefrom the temperature of the bloom, the slab, the billet or the ingotjust after casting to 450° C. at a cooling rate of 0.5° C./s or more, sothat the relationship between the total number N and the diameter Xsatisfies the following formula (1):log N≦0.4742+17.629 exp(−0.1 133 X)  (1)wherein N means the total numberof precipitates and inclusions, having a diameter of not smaller than 1μm which are found in 1 mm² of the alloy; and X means the diameter in μmof the precipitates and the inclusions having a diameter of not smallerthan 1 μm.
 10. A method for producing a copper alloy, comprising coolinga bloom, a slab, a billet or an ingot obtained by melting a copper alloyhaving a chemical composition described in claim 1 followed by coolingin at least a temperature range from the temperature of the bloom, theslab, the billet or the ingot just after casting to 450° C. at a coolingrate of 0.50° C./s or more, and performing working in a temperaturerange of 600° C. or lower, so that the relationship between the totalnumber N and the diameter X satisfies the following formula (1):log N≦0.4742+17.629 exp(−0.1133 X)  (1) wherein N means the total numberof precipitates and inclusions, having a diameter of not smaller than 1μm which are found in 1 mm² of the alloy; and X means the diameter in μmof the precipitates and the inclusions having a diameter of not smallerthan 1 μm.
 11. A method for producing a copper alloy, comprising coolinga bloom, a slab, a billet, or a ingot obtained by melting a copper alloyhaving a chemical composition described in claim 1 followed by coolingin at least a temperature range from the temperature of the bloom, theslab, the billet or the ingot just after casting to 450° C. at a coolingrate of 0.5° C./s or more, performing working in a temperature range of600° C. or lower, and then performing heat treatment of holding for 30seconds or more in a temperature range of 150 to 750° C., so that therelationship between the total number N and the diameter X satisfies thefollowing formula (1):log N≦0.4742+17.629 exp(−0.1133 X)  (1)wherein N means the total numberof precipitates and inclusions, having a diameter of not smaller than 1μm which are found in 1 mm² of the alloy; and X means the diameter in μmof the precipitates and the inclusions having a diameter of not smallerthan 1 μm.
 12. A method for producing a copper alloy according to claim11, wherein the working in a temperature range of 600° C. or lower andthe heat treatment of holding for 30 seconds or more in a temperaturerange of 150 to 750° C. are performed for a plurality of times.
 13. Themethod for producing a copper alloy according to claim 1, wherein theworking in a temperature range of 600° C. or lower is performed afterthe final heat treatment.